After ending 2015 with three wins and promises of pulling closer to Mercedes, Ferrari instead slid backward.

There have been no victories, just one podium finish in the last nine races and Ferrari is once again fending off questions about discord within Formula 1's most popular team.

'Far from ideal'

Just look at last weekend's race at the US Grand Prix; After a disappointing qualifying in which both drivers started on the third row, Sebastian Vettel finished fourth and Kimi Raikkonen didn't finish at all when he was forced to return to the garage after leaving a pit stop with an improperly attached wheel.

Judged by race officials as an unsafe release, Ferrari was hit with a fine. Seeing sparks fly as he pulled away, Raikkonen put the car in reverse for a humiliating return drive back downhill as Ferrari slipped further behind Red Bull for second place in the team championship, which it hasn't won since 2008.

"Far from ideal" is how the deadpan Raikkonen summed it up.

The same could be said about Ferrari's entire season as F1 heads to the 2016 Mexican Grand Prix this weekend.

Ferrari landed in Mexico last season full of optimism. Vettel's had scored the non-Mercedes wins all year. He was a regular on the podium and Ferrari was cruising toward a second-place finish in the constructor's championship.

There's been none of the same confidence in 2016. The Ferrari drivers - both former world champions - have made more noise with their mouths than their cars, with Vettel complaining about slow drivers and he and Raikkonen both criticising the defensive tactics of Red Bull's brash Dutch teenager Max Verstappen as dangerous.

'Climate of fear'

Luca Baldisseri, Ferrari's former chief engineer who left the team after last season, caused a stir around Formula One before the 2016 US Grand Prix when he told Italian media that Ferrari leadership had created a "climate of fear."

Baldiserri said: "They are no longer a team, but a group of frightened people."

"It's an old story. Ferrari in Italy is like the Italian football national team. I think pressure is normal, having tension is normal, having criticism is normal, so you have to live with that. Then, sometimes it's going too far," Arrivabene said. "This is part of the job ... if you work for a brand like Ferrari, you have to accept all of this, like it or not. The atmosphere inside the house is completely different to what people thought about, or what you are reading sometimes in the newspaper."

To be fair, Ferrari is far from the panic that had set in in 2014 when Mercedes blew everyone away with their new V6 turbo hybrid engines. Ferrari had scrapped its way back to best-of-the-rest in 2015, making this season's results so frustrating.

And Red Bull's resurgence has some thinking that's the team to knock off Mercedes in 2017. Red Bull teammates Verstappen and Daniel Ricciardo have the only non-Mercedes win this year and those two are considered likely contenders for future world titles.

Ferrari hasn't won a driver's championship since Raikkonen in 2007 and the last time it was seriously in the hunt was 2012 with Fernando Alonso. The pairing of Raikkonen with Vettel, who won four titles with Red Bull, gives Ferrari a powerful 1-2 punch behind the wheel if they can get competitive cars.

'My contract is fine for 2017'

Vettel is under contract with Ferrari through next season and said he won't think about starting negotiations until after this season is finished.

Vettel said: "I don't think it's important to look into details as such. My contract is all fine for next year."

The 2016 Mexican Grand Prix at the Autodromo Hermanos Rodriguez was not a good experience for Ferrari in 2015.

Brimming with confidence from a good drive in Texas his team's season-long surge, Vettel qualified third but was knocked back by a tire puncture on the first lap, then knocked out when aggressive driving led to a late crash. Raikkonen also didn't finish after breaking a real axle in a bump with Williams driver Valterri Bottas.

It was the first time since 2006 that both Ferrari cars failed to finish a race.